Self-propelled vacuum cleaner

ABSTRACT

A self-propelled vacuum cleaner having right and left side brushes for directing dust on a floor surface toward the inside of the bottom of the cleaner body. The right side brush rotates in a counterclockwise direction as viewed from top on a rotary shaft, which is tilted so that the lower end is located toward the right of and the rear of the cleaner body as compared with the upper end. The left side brush rotates in a clockwise direction as viewed from top on a rotary shaft, which is tilted so that the lower end is located toward the left of and the rear of the cleaner body as compared with the upper end. The tilted rotary shafts can prevent the outer portions of the side brushes at their rear portions from contacting a floor surface, thereby preventing dust collected by the front portions of the side brushes from being scattered to the outside of the cleaner body by the rear portions of the brushes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a self-propelled vacuum cleaner, and more particularly to a self-propelled vacuum cleaner having side brushes for directing dust on a floor surface toward the inside of the cleaner body.

2. Description of the Related Art

Self-propelled vacuum cleaners are known that have drive motors mounted in the main body thereof for driving wheels so as to clean a surface while controlling movement of the main body by controlling the drive motors. Especially in recent years, self-propelled vacuum cleaners capable of autonomous movement have been developed that can clean a surface while autonomously determining an area to be cleaned based on output signals of a plurality of sensors.

Some of the conventional self-propelled vacuum cleaners have side brushes. The side brushes are mounted at both sides of a cleaner body, and rotate on rotary shafts extending in the vertical direction to sweep dust on a floor surface toward the inside of the cleaner body. However, in such a conventional self-propelled vacuum cleaner, since the rotary shafts of the side brushes are arranged to extend in the vertical direction, the entire surfaces of the side brushes that face a floor come in contact with the floor. Accordingly, the side brushes can possibly direct dust, which is collected at the inside of the cleaner body by the front portions of the brushes, toward the outside of the cleaner body to scatter it by the rear portions of the brushes.

A known self-propelled vacuum cleaner has side brushes with rotary shafts each mounted to be pivotable about an axis extending in the front-rear direction of the cleaner body and biased to be angled with respect to the vertical direction so that the side brushes come in contact with a floor surface from the outer ends thereof (see, for example, Japanese laid-open patent publication HEI 5-228090).

However, the self-propelled vacuum cleaner as disclosed in the Japanese laid-open patent publication HEI 5-228090 has the following problem. The cleaner can keep part of the surfaces of the side brushes that face a floor from contacting the floor due to the rotary shafts arranged in the cleaner body to be angled with respect to the vertical direction, but since the rotary shafts are biased so that the outer ends of the side brushes come in contact with a floor, the cleaner cannot prevent the outer end portions of the side brushes at the rear portions from contacting with a floor. Accordingly, the cleaner cannot sufficiently prevent dust scattering at the rear portions of the side brushes.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a self-propelled vacuum cleaner that can prevent dust gathered up by the front portion of a side brush from being scattered to the outside of the cleaner body by the rear portion of the side brush, thereby having improved dust collecting power.

According to a first aspect of the present invention, the above object is achieved by a self-propelled vacuum cleaner comprising: a pair of side brushes for directing dust on a floor surface toward an inside of a bottom of a main body of the cleaner, the side brushes including a right side brush that rotates in a counterclockwise direction, as viewed from top, on a rotary shaft and a left side brush that rotates in a clockwise direction, as viewed from top, on a rotary shaft, wherein the rotary shaft of the right side brush is angled with respect to a vertical axis of the main body so that a lower end of the rotary shaft is located toward the right of and the rear of the main body as compared with an upper end of the rotary shaft, and wherein the rotary shaft of the left side brush is angled with respect to the vertical axis of the main body so that a lower end of the rotary shaft is located toward the left of and the rear of the main body as compared with an upper end of the rotary shaft.

According to the first aspect of the present invention, the rotary shaft of the right side brush rotating in the counterclockwise direction as viewed from top is tilted so that the lower end is located toward the right and the rear of the cleaner body as compared with the upper end while the rotary shaft of the left side brush rotating in the clockwise direction as viewed from top is tilted so that the lower end is located toward the left of and the rear of the cleaner body as compared with the upper end. By such a configuration, the outer portions of the side brushes at the rear portions can be prevented from coming in contact with a floor surface. Therefore, the side brushes can prevent dust gathered up by the front portions thereof from being scattered to the outside of the cleaner body by the rear portions thereof.

Preferably, in the self-propelled vacuum cleaner, each of the side brushes includes the rotary shaft to be rotated, a brush holder mounted on a lower end of the rotary shaft, and a mop-like brush body that spreads out like a truncated cone with an upper end fixed to the brush holder and a lower end free, and an inner portion of each of the side brushes comes in contact with a floor surface under pressure higher than that at an outer portion of each of the side brushes.

By such a configuration, since the inner portions of the side brushes contact a floor surface under pressure higher than that at the outer portions of the side brushes, dust collecting power at the inside of the bottom of the cleaner body can be enhanced. Further, since the brush body of the side brush is shaped like a mop to spread out like a truncated cone with the free lower end, the side brush can cover a relatively large area to be cleaned. Accordingly, the cleaner can have improved dust collecting power.

Preferably, the self-propelled vacuum cleaner further comprises a dust collection unit, the dust collection unit including: a main brush that is located behind the side brushes and rotates on a shaft extending in a width direction of the main body so as to bring up dust collected at the inside of the bottom of the main body by the side brushes; a dust suction fan for sucking the dust brought up by the main brush; and a dust box for collecting the dust sucked by the dust suction fan.

Preferably, the self-propelled vacuum cleaner further comprises: obstacle detection means for detecting an obstacle while the cleaner moves; and position identifying means for identifying a position of the cleaner while the cleaner moves, wherein the cleaner moves on and clean a surface while automatically determining an area to be cleaned based on outputs of the obstacle detection means and the position identifying means.

By such a configuration, the self-propelled vacuum cleaner autonomously moves on and cleans a surface while automatically determining an area to be cleaned, so that it generally avoids a redundant cleaning operation for an already cleaned area. As described above, the side brushes of the self-propelled vacuum cleaner can prevent dust gathered up by the front portions thereof from being scattered to the outside of the cleaner body by the rear portions thereof. Therefore, dust scattering by the rear portions of the side brushes toward already cleaned areas can be inhibited, and thus dust collecting performance of the cleaner can be improved.

While the novel features of the present invention are set forth in the appended claims, the present invention will be better understood from the following detailed description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a cleaner body of a self-propelled vacuum cleaner according to an embodiment of the present invention.

FIG. 2 is a block diagram of the cleaner body.

FIG. 3A, FIG. 3B, and FIG. 3C are a top view, a front view, and a left side view, respectively, showing a dust collection unit in the cleaner.

FIG. 4A, FIG. 4B, and FIG. 4C are a top view, a front view, and a left side view, respectively, showing a dust collecting operation of the cleaner.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the accompanying drawings, a self-propelled vacuum cleaner embodying the present invention will be described. FIG. 1 shows a cleaner body 1 of the self-propelled vacuum cleaner according to this embodiment, which is a device that autonomously moves on a floor surface to clean the floor surface. The cleaner body 1 comprises: a behavior control unit 2 that determines an area to be cleaned based on output signals of a plurality of sensors S1, S2, etc. and controls a cleaning operation of the cleaner body 1; and a dust collection unit 3 that moves around a floor surface based on control signals from the behavior control unit 2 to remove dust from the floor. In FIG. 1, the cleaner body 1 comprising the behavior control unit 2 and the dust collection unit 3 is separated into the behavior control unit 2 and the dust collection unit 3 for purposes of illustration.

The dust collection unit 3 comprises a pair of side brushes 30R and 30L provided at right and left sides of the cleaner body 1 for directing dust on a floor surface toward the inside of the bottom of the cleaner body 1, side brush motors 34 that rotates the side brushes 30R and 30L, a main brush 40 that brings up the dust collected at the inside of the bottom of the cleaner body 1 by the side brushes 30R and 30L, a main brush motor 41 that rotates the main brush 40, a roller 42 that rotates following the rotation of the main brush 40, a dust suction fan 51 that sucks the dust brought up by the main brush 40, and a dust box 52 that collects the dust sucked by the dust suction fan 51.

The dust collection unit 3 further comprises a right wheel 60R and a left wheel 60L that are provided at both sides of the cleaner body 1, a right wheel motor 61R and a left wheel motor 61L that rotate the right and left wheels 60R and 60L, respectively, and an idler wheel 62 that is located in front of the two wheels 60R and 60L and rotates following the rotation of the two wheels 60R and 60L. The respective components of the dust collection unit 3 will be described in more detail below.

Referring now to FIG. 2, a block configuration of the cleaner body 1 will be described. The cleaner body 1 comprises: a front sensor S1, a ceiling sensor S2, and a step sensor S3 that are included in obstacle detection means for detecting an object and so on; and a geomagnetic sensor S4, an acceleration sensor S5, a map information memory 71 that are included in position identifying means for identifying the position of the cleaner body 1 while the cleaner body 1 moves. Each of the front sensor S1, the ceiling sensor S2, and the step sensor S3 is an optical distance sensor for example. The front sensor S1 monitors the area in front of the cleaner body 1 downward diagonally so as to detect and measure distances to obstacles such as a step, a wall, a pillar, a furniture, a leg of a table or a bed, and the like. The ceiling sensor S2 monitors the area in front of the cleaner body 1 upward diagonally so as to detect obstacles located above and in front of the cleaner body 1 (as to whether or not it can pass through, under a table, a bed or the like) and measures heights of and distances to the obstacles. The step sensor S3 monitors the area slightly in front of the cleaner body 1 downward diagonally so as to detect and measure distances to obstacles. The acceleration sensor S5 detects accelerations acting on the cleaner body 1 in up-down direction, forward-backward direction and left-right direction, respectively.

The cleaner body 1 further comprises an operating unit 72 to be operated by a user, a controller 73 to control the respective components of the cleaner body 1, and a battery 74 to supply power to the cleaner body 1. The operating unit 72 is operated by a user to start and stop a cleaning operation of the cleaner body 1, and to make various other settings.

The controller 73 controls the respective components of the cleaner body 1 based on output signals of the respective sensors S1 to S5 and so on, and comprises a position and direction determination section 73 a, a movement control section 73 b, and a cleaning operation control section 73 c.

The position and direction determination section 73 a creates map information about already cleaned areas and areas where an obstacle is present based on outputs of the front sensor S1, the ceiling sensor S2, and the step sensor S3, and stores the map information in a map information memory 71. Further, the position and direction determination section 73 a time-integrates an output value of the acceleration sensor S5 in the forward-backward direction and thereby calculates a traveling speed of the cleaner body 1. Based on the calculated traveling speed and a travel time, the position and direction determination section 73 a calculates a travel distance. The position and direction determination section 73 a further determines the direction in which the cleaner body 1 faces based on an output value of the geomagnetic sensor S4 in accordance with the direction of the geomagnetic field.

The movement control section 73 b controls directions and speeds of the rotations of the right wheel motor 61R and the left wheel motor 61L independently so as to control a moving direction and a traveling speed of the cleaner body 1. The map information stored in the map information memory 71 is updated at all times during a cleaning operation so that the cleaner body 1 carries out the cleaning operation while reading the updated map information.

The cleaning operation control section 73 c controls the rotations of the side brush motors 34, the main brush motor 41, and a dust suction motor 51 a that rotates the dust suction fan 51 so as to adjust the dust collecting power.

Referring now to FIG. 3, the configuration of the dust collection unit 3 is described in detail. Each of the side brushes 30R and 30L comprises a rotary shaft 31R or 31L to be rotated by the side brush motor 34, a brush holder 32R or 32L mounted on the lower end of the rotary shaft 31R or 31L, and a mop-like brush body 33R or 33L that spreads out like a truncated cone with the upper end fixed to the brush holder 32R or 32L and the lower end free. Since the side brushes 30R and 30L have the brush bodies 33R and 33L each shaped like a mop to spread out like a truncated cone with the free lower end, they can cover a relatively large area to be cleaned. Accordingly, the cleaner body 1 can have improved dust collecting power.

The rotary shaft 31R of the right side brush 30R is tilted, namely, angled with respect to the vertical axis of the cleaner body so that the lower end 31 a is located toward the right, namely, outside of and the rear of the cleaner body 1 as compared with the upper end. The rotary shaft 31L of the left side brush 30L is tilted, namely, angled with respect to the vertical axis so that the lower end 31 a is located toward the left, namely, outside of and the rear of the cleaner body 1 as compared with the upper end. The side brush motors 34 are mounted on the rotary shafts 31R and 31L to rotate the right side brush 30R and the left side brush 30L in a counterclockwise direction r1 and a clockwise direction r2, respectively as viewed from top. Thereby, dust on a floor surface is directed toward the inside of the cleaner body 1.

The titled rotary shafts 31R and 31L of the side brushes 30R and 30L allow the inner portions of the side brushes 30R and 30L to contact a floor surface under pressure higher than that at the outer portions of the side brushes 30R and 30L, thereby enhancing the dust collecting power of the cleaner body 1 at the inner portion of the bottom.

The main brush 40 is located behind the side brushes 30R and 30L. The main brush 40 is rotated by the main brush motor 41 in a direction indicated by an arrow r3 about a shaft 40 a extending in a width direction of the cleaner body 1. Thereby, the main brush 40 brings up dust collected at the inside of the bottom of the cleaner body 1. Disposed in front of the main brush 40 is the roller 42. The roller 42 rotates in a direction indicated by an arrow r4 following the rotation of the main brush 40. Accordingly, the roller 42 cooperates with the main brush 40 to bring up the dust.

Disposed above the main brush 40 is a nozzle 53. The nozzle 53 sucks the dust brought up by the main brush 40 into the dust box 52, by air flow produced by the dust suction fan 51. The nozzle 53 has a valve 53 a at the inlet facing the main brush 40. The valve 53 a allows dust to pass through the nozzle only when the dust suction fan 51 is in operation.

Referring now to FIG. 4, a cleaning operation of the cleaner body 1 will be described. The cleaner body 1 carries out a cleaning operation using the side brushes 30R and 30L, the main brush 40, the dust suction fan 51 and so on while moving in a forward direction F by rotating the right and left wheels 60R and 60L. For example, as the left side brush 30L is rotated in the direction r2, dust on a position P1 on a floor surface is brought via a position P2 to the inside of the bottom of the cleaner body 1. Since the rotary shafts 31R and 31L of the side brushes 30R and 30L are tilted as described above, the outer portions of the side brushes 30R and 30L at their rear portions can be kept from contacting the floor surface. Accordingly, dust gathered up by the front portions of the side brushes 30R and 30L can be prevented from being brought out to e.g. a position P5. In other words, the side brushes 30R and 30L can prevent dust scattering by the rear portions thereof. As described above, the autonomous self-propelled vacuum cleaner stores already cleaned areas to avoid a redundant cleaning operation for such already cleaned areas. Accordingly, by preventing the side brushes 30R and 30L from scattering dust toward already cleaned areas, the dust collecting performance of the cleaner can be enhanced.

Dust collected at the inside of the bottom of the cleaner body 1 by the side brushes 30R and 30L is brought up toward the inlet of the nozzle 53 that faces the main brush (position P3) by the main brush 40 and the roller 42. Thereafter, the dust is transported to a position P4 within the nozzle 53 by the air flow produced by the dust suction fan 51 so as to be sucked into the dust box 52.

The present invention has been described above using a presently preferred embodiment, but those skilled in the art will appreciate that various modifications are possible. Accordingly, all such modifications are intended to be included within the spirit and scope of the present invention. For example, the cleaner body 1 is not limited to a so-called autonomous vacuum cleaner, but can be a self-propelled vacuum cleaner having at least a pair of right and left side brushes.

This application is based on Japanese patent application 2004-22413 filed in Japan dated Jan. 30, 2004, the contents of which are hereby incorporated by references. 

1. A self-propelled vacuum cleaner, comprising: a pair of side brushes for directing dust on a floor surface toward an inside of a bottom of a main body of the cleaner, the side brushes including a right side brush that rotates in a counterclockwise direction, as viewed from top, on a rotary shaft and a left side brush that rotates in a clockwise direction, as viewed from top, on a rotary shaft, wherein the rotary shaft of the right side brush is angled with respect to a vertical axis of the main body so that a lower end of the rotary shaft is located toward the right of and the rear of the main body as compared with an upper end of the rotary shaft, and wherein the rotary shaft of the left side brush is angled with respect to the vertical axis of the main body so that a lower end of the rotary shaft is located toward the left of and the rear of the main body as compared with an upper end of the rotary shaft.
 2. The self-propelled vacuum cleaner according to claim 1, wherein each of the side brushes includes the rotary shaft to be rotated, a brush holder mounted on a lower end of the rotary shaft, and a mop-like brush body that spreads out like a truncated cone with an upper end fixed to the brush holder and a lower end free, and wherein an inner portion of each of the side brushes comes in contact with a floor surface under pressure higher than that at an outer portion of each of the side brushes.
 3. The self-propelled vacuum cleaner according to claim 2, further comprising a dust collection unit, the dust collection unit including: a main brush that is located behind the side brushes and rotates on a shaft extending in a width direction of the main body so as to bring up dust collected at the inside of the bottom of the main body by the side brushes; a dust suction fan for sucking the dust brought up by the main brush; and a dust box for collecting the dust sucked by the dust suction fan.
 4. The self-propelled vacuum cleaner according to claim 2, further comprising: obstacle detection means for detecting an obstacle while the cleaner moves; and position identifying means for identifying a position of the cleaner while the cleaner moves, wherein the cleaner moves on and clean a surface while automatically determining an area to be cleaned based on outputs of the obstacle detection means and the position identifying means. 